Fiber-optic gyroscopes are used to measure rotation in navigation applications such as aircraft, missiles, satellites, and other vehicles. Fiber-optic gyroscopes measure angular rotation by determining the phase difference in light waves that propagate in opposite directions through a coil of optical fiber. Light waves that propagate through the coil in the opposite direction of the rotation take a shorter time than light waves that propagate in the direction of rotation. Many fiber-optic gyroscopes employ a closed feedback loop phase modulation scheme to increase the sensitivity of the fiber-optic gyroscope to rotation. These schemes must constantly compensate for rotation induced phase differentials to maintain a lock on the desired modulation points. One problem with these schemes is that electronics within the feedback scheme have limited output range so that feedback signals must be periodically reset in order to stay within the operating range of the electronics.
Currently, to stay within the operating range of the electronics, the rotation compensation component of the feedback scheme is reset whenever a value that produces a 2π value in optical phase is reached. While addressing the problem of the electronics having a limited output range, resetting the feedback scheme on this basis generates rate dependent sinusoidal signal (RDSs) in the gyroscopes frequency band-of-interest. Rate dependent sinusoidal signals thus create problems calculating the rotation of the vehicle.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for improved feedback schemes for optical gyroscopes.